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Leapfrog Sum Trick Worksheet

Maths tricks trick 25: The leapfrog sum trick · Set 665 · 40 questions
TalentJR

The trick (Seventh times eleven): A leapfrog list: start with two numbers, then each number is the sum of the two before it, up to 10 numbers. Find the 7th number. Multiply it by 11 (the number with a 0 on the end, plus the number): that is the total of all 10.

NameDateTime takenScore ___ / 40
  1. 1.5 + 5 + 10 + 15 + 25 + 40 + 65 + 105 + 170 + 275 =
  2. 2.Leapfrog list (each number is the sum of the two before it): 9, 5, 14, 19, 33, 52, 85, 137, 222, 359. What is 11 × the 7th number?
  3. 3.A leapfrog list starts 7, 2 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  4. 4.Leapfrog list (each number is the sum of the two before it): 4, 9, 13, 22, 35, 57, 92, 149, 241, 390. What is 11 × the 7th number?
  5. 5.A leapfrog list starts 2, 4 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  6. 6.A leapfrog list starts 6, 7 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  7. 7.8 + 9 + 17 + 26 + 43 + 69 + 112 + 181 + 293 + 474 =
  8. 8.8 + 3 + 11 + 14 + 25 + 39 + 64 + 103 + 167 + 270 =
  9. 9.Leapfrog list (each number is the sum of the two before it): 2, 3, 5, 8, 13, 21, 34, 55, 89, 144. What is 11 × the 7th number?
  10. 10.Leapfrog list (each number is the sum of the two before it): 1, 2, 3, 5, 8, 13, 21, 34, 55, 89. What is 11 × the 7th number?
  11. 11.Leapfrog list (each number is the sum of the two before it): 1, 7, 8, 15, 23, 38, 61, 99, 160, 259. What is 11 × the 7th number?
  12. 12.2 + 1 + 3 + 4 + 7 + 11 + 18 + 29 + 47 + 76 =
  13. 13.1 + 3 + 4 + 7 + 11 + 18 + 29 + 47 + 76 + 123 =
  14. 14.8 + 5 + 13 + 18 + 31 + 49 + 80 + 129 + 209 + 338 =
  15. 15.5 + 7 + 12 + 19 + 31 + 50 + 81 + 131 + 212 + 343 =
  16. 16.Leapfrog list (each number is the sum of the two before it): 1, 9, 10, 19, 29, 48, 77, 125, 202, 327. What is 11 × the 7th number?
  17. 17.Leapfrog list (each number is the sum of the two before it): 4, 8, 12, 20, 32, 52, 84, 136, 220, 356. What is 11 × the 7th number?
  18. 18.A leapfrog list starts 7, 1 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  19. 19.A leapfrog list starts 9, 8 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  20. 20.A leapfrog list starts 7, 9 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  21. 21.Leapfrog list (each number is the sum of the two before it): 2, 5, 7, 12, 19, 31, 50, 81, 131, 212. What is 11 × the 7th number?
  22. 22.9 + 3 + 12 + 15 + 27 + 42 + 69 + 111 + 180 + 291 =
  23. 23.Leapfrog list (each number is the sum of the two before it): 9, 1, 10, 11, 21, 32, 53, 85, 138, 223. What is 11 × the 7th number?
  24. 24.A leapfrog list starts 6, 5 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  25. 25.A leapfrog list starts 1, 4 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  26. 26.Leapfrog list (each number is the sum of the two before it): 4, 5, 9, 14, 23, 37, 60, 97, 157, 254. What is 11 × the 7th number?
  27. 27.A leapfrog list starts 5, 5 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  28. 28.Leapfrog list (each number is the sum of the two before it): 9, 3, 12, 15, 27, 42, 69, 111, 180, 291. What is 11 × the 7th number?
  29. 29.Leapfrog list (each number is the sum of the two before it): 7, 4, 11, 15, 26, 41, 67, 108, 175, 283. What is 11 × the 7th number?
  30. 30.7 + 3 + 10 + 13 + 23 + 36 + 59 + 95 + 154 + 249 =
  31. 31.9 + 6 + 15 + 21 + 36 + 57 + 93 + 150 + 243 + 393 =
  32. 32.Leapfrog list (each number is the sum of the two before it): 2, 9, 11, 20, 31, 51, 82, 133, 215, 348. What is 11 × the 7th number?
  33. 33.9 + 9 + 18 + 27 + 45 + 72 + 117 + 189 + 306 + 495 =
  34. 34.A leapfrog list starts 8, 5 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  35. 35.Leapfrog list (each number is the sum of the two before it): 4, 3, 7, 10, 17, 27, 44, 71, 115, 186. What is 11 × the 7th number?
  36. 36.5 + 3 + 8 + 11 + 19 + 30 + 49 + 79 + 128 + 207 =
  37. 37.7 + 8 + 15 + 23 + 38 + 61 + 99 + 160 + 259 + 419 =
  38. 38.9 + 2 + 11 + 13 + 24 + 37 + 61 + 98 + 159 + 257 =
  39. 39.7 + 4 + 11 + 15 + 26 + 41 + 67 + 108 + 175 + 283 =
  40. 40.A leapfrog list starts 3, 9 and each next number is the sum of the two before it. What do the first 10 numbers add up to?

Answer key

  1. 715
  2. 935
  3. 561
  4. 1012
  5. 462
  6. 946
  7. 1232
  8. 704
  9. 374
  10. 231
  11. 671
  12. 198
  13. 319
  14. 880
  15. 891
  16. 847
  17. 924
  18. 473
  19. 1199
  20. 1177
  21. 550
  22. 759
  23. 583
  24. 770
  25. 407
  26. 660
  27. 715
  28. 759
  29. 737
  30. 649
  31. 1023
  32. 902
  33. 1287
  34. 880
  35. 484
  36. 539
  37. 1089
  38. 671
  39. 737
  40. 957

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